Electric water heater



Patented Feb. 24, 1942 UNITED STATES PATENT CFFICE 2Claims.

This invention relates to electric water heaters of the immersion type, more particularly to the type employed to heat water in closed containers such as hot water bottles.

In use with heaters of this character the water itself acts as a conductor and at the same time forms an electrical resistance causing it to become heated.

Heaters of this character have heretofore been devised to accomplish the above stated purpose but have not proven satisfactory for the reason that the metallic electrodes employed therein (while functioning properly when rst used) co1- lect or become coated with elements present in water such as lime or alkali until they eventually become insulated thereby not only reducing the efliciency of `the heater but finally rendering it useless.

Further in types of the aforesaid heaters in which metal electrodes are employed there is always present danger of generating gas for example chlorine if there should be salt present in the water.

It is therefore an object of the present invention to provide a water heater of the character described in which the electrodes will not collect or become coated with elements present in the water being heated.

Another object is to provide a heater of this character that will not generate gas while in use regardless of any gas producing elements present in the water.

Other objects and advantages will be apparent from the following description reference being had to the accompanying drawing, in which:

Fig. 1 is a side elevation of the water heater applied to hot water bag.

Fig. 2 is a vertical section on an enlarged scale taken on line 2-2 of Fig. 1.

Fig. 3 is a top plan view taken in the direction of the arrow 3 of Fig. 2 parts being broken away and shown in section.

Fig. 4 is a horizontal section taken on line 4-4 l of Fig. 2.

Fig. 5 is a detail section taken on line 5-5 of Fig. 2.

Fig. 6 is an enlarged fragmentary detail section taken on the same plane as Fig. 2 showing the connection of the transmission line wire to the outer electrode.

Referring more specically to the drawing I0 designates the main body of the heater which is preferably of cylindrical shape having a depending portion Ii that is externally screw connection with for example a hot water bottle B indicated in dotted lines in Fig. l.

The body Il is formed of electrical insulating material preferably Bakelite and has a screw threaded portion I3 depending therefrom for connection with a protective housing I4 also formed of insulating material, thereby rendering the heater electrically insulated against a shock to the person handling the same after it has been connected to a source of electrical current, the housing having a plurality of openings I4a for admission of water to come in contact with the electrodes hereinafter described.

Formed in the depending portion I3 of the body portion is a recess of non circular shape in cross section preferably hexagonal in which is positioned a member i5 formed of brass or other electrical conductive material.

Rigidly secured to member l5 as indicated at lia is a thermostatic element I6 of usual form consisting of two metal members each having a different coefficient of expansion secured together at their upper ends as indicated l1.

Thermostatc element i6 serves to break the electrical current after the water has reached a predetermined degree of heat and also acts as a conductor while the water is being heated. Embedded in the body is a connector post I8 having an upwardly projecting portion I9 and a threaded opening in its lower portion 2li through which extends an adjustable contact screw 22 which is also threaded in body portion. The inner end of the contact screw engages point I1 of the thermostatic element and has a knob 24 threaded on its outer end for adjusting the same in relation to said thermostatic element whereby the degree of heat may be regulated.

Formed on the knob is a pointer 24a adapted to register with indicia formed on the face of the body portion and is held against turning on the contact screw by a set screw 25.

Projecting from the body il is a pin 26 that enters an arcuate groove 2 formed in the knob which limits turning movement of the contact screw so that it may not be turned out of engagement with the thermostatic element. Arranged in the body is a spring 2l the free end of which engages the contact screw and holds the same in adjusted position.

Threadedly connected to member i5 as indicatedat 2S is a rod 3l that forms the center electrode. This rod is formed of carbon or graphite and is encased in or has a thin layer of metal preferably copper thereon 3| in order threaded as indicated at i2 in Figs l and 2 for 55 t0 strengthen the same and prevent corrosion.

The metal layer 3| is very thin in cross section and is applied thereto by the electrolytic plating process. Engaging the threaded portion 28 of rod 3U is a nut 32 that serves to hold the same in tight engagement with the member I8 also to prevent any leakage of water into the interior of the body I0. In assembling the nut is rst threaded on the rod, which is then screwed into member l5 the opening in the body III below the member filled with Bakelite cement indicated I3 and the nut tightened thereby establishing a fluid tight seal around the rod.

Engaging a reduced diameter portion formed on the body I is a tubular member 34 formed of carbon or graphite and serves as the other electrode of the Heater. The outer surface of member 34 encased in metal indicated at I in order to strengthen the same also to form means for connecting it with the electrical transmission wire 38. y

'I'he lower end of wire 38 extends into a cavity 38 formed in the' upper end of tubular member 34 and is secured to the metalzed portion by solder or the like indicated at 39a in Fig. 6. Wire 38 extends upwardly through an opening in the body and is secured to a post 4| by a screw 40 which also serves to hold the post in place on the body, it being understood that posts I9 and 4i are adapted to be inserted into a usual plug of a lamp socket not shown when in use.

It will be understood that in assembling the tubular member 34 and the protective housing i4 are covered with Bakelite cement at their points of Contact with the body l0 and are permanently sealed thereby.

Removably mounted on the body i0 is a cap 42 formed of insulating material and is secured thereto by screws 44.

Encircling the housing and engaging a shoul- Illa der formed on the body is a rubber washer 45 for forming a fluid tight seal when the heater is applied to hot water bottles or the like.

When in use water in contact with the electrodes I4 and lll acts as a conductor and also oiers resistance to the current passing therethrough causing the temperature to rise as previously referred to until the circuit is automatically broken by the thermostat II after the water has reached a predetermined degree of heat.

It will also be noted that as the electrodes are formed o! carbon or graphite they will not become coated with elements present in the water.

I claim:

1. An electrical water heater of the immersion type comprising a plug formed of electrical insulating material, a tubular electrode secured at one end to said plug, a second electrode within said tubular electrode secured at one end to said plug, and a housing of insulating material enclosing said electrodes, said housing being supported from the plug independent of any connection to the electrodes and adapted for ready removal from the plug for gaining access to the electrodes.

2. An electrical Water heater of the immersion type comprising a plug i'onned of electrical insulating material, a tubular electrode secured at one end to said plug and having its opposite end open, a second electrode within said tubular electrode secured at one end to said plug, and a housing of insulating material enclosing said elec,- trodes and supported from the plug independent o! any connection to the electrodes, said housing having a drain opening in its free end and adapted for ready removal from the plug for gaining access to the electrodes.

HARRY A. RUSH. 

